Such electrical contact components are utilized, for example, as plug contacts in plug connectors or in plug-connector connections in the automotive industry.
The design of the contact elements is of great importance for the reliability of plug connectors. The utilized contact carrier material together with the utilized contact surface determines during operation the aging behavior and the lifetime characteristics.
The known electrical contacts for this use consist usually of a base body (metal strip), in particular made of a Cu alloy, and a contact material applied galvanically, via hot dip tinning or via cladding. In particular gold, silver or tin layers are used for this purpose. A powder-metallurgical manufacture of the contact points, which are welded onto the contact area, is not possible for plug connectors, in particular the female part, since the contact area is being reshaped and thus is not freely accessible.
Thus a sufficient wear resistance and a low contact resistance of the plug connector system can be achieved during the planned lifetime only for operating voltages up to 14 Volt in view of the up to now demanded marginal conditions.
This, however, no longer applies when increased demands are made of the plug contacts, for example, with respect to the possible danger of the electric-arc formation in a 42 V electrical system in the automotive industry, or with respect to the placing of the plug contact in the direct vicinity of the motor due to high temperatures. The problems of an electric-arc creation is already known in the case of switching contacts, for example in the case of relays. The special contact layers are in the case of switching contacts applied in an additional operation through soldering or welding onto the carrier material. The contact material itself is manufactured in a preceding operating step by sintering or extrusion.
This phenomena appears only at a voltage above 16 Volt in common plug connections in the automotive field. The danger of the electric-arc formation and of the contact bouncing during plugging in or pulling out of the plug connector connections exists in a 42 V electrical system. The electric arc causes locally a heating up of the material to above 1000° C., this leads to the contact surfaces of the plug connectors being burnt off. It is also possible for incompletely plugged connections to cause through vibrations created during driving such electric arcs, which result in a crawling burning away and in the end a total breakdown of a plug connection.
A material for electrical contacts made of silver and carbon is known from the reference DE 195 03 184 Cl. This reference deals with a sintered material, which due to a certain carbon-black content has an improved burning characteristic. The carbon is for its manufacture added in the form of carbon black with a primary particle size of less than 150 nm to silver, the mixture is isostatically cold pressed and thereafter sintered. With the same goal, namely to improve the burning characteristics and the welding resistance, a composite material for electrical contacts is known from the reference DE 41 11 683 C2. The composite material consists of silver or a silver alloy with a carbon content, which is processed in the form of a combination of a carbon powder and carbon fibers in a mass ratio of 10:1 to 1:10 with the metal component.
The disadvantage of such materials is that their manufacture and further processing is not suited for the manufacture of electrical contact components in connection with a reshaping of the metal strips.
Furthermore, a device with an atomizer is known from the reference EP 0 225 080 B1, with which device a jet of a liquid metal is atomized with a gas jet into a spray mist consisting of droplets. The atomizer is thereby supported tiltably about a stationary axis in such a manner that the spray mist is evenly distributed on a moving band-shaped substrate or another collecting device. The device is used for the manufacture of thin metal strips or for coating of strips.
A surface-like even distribution of the applied metal layer is indeed achieved with this manufacturing method, however, it permits first of all only a simple material selection with one melt component. Furthermore an atomizer movable relative to the metal jet represents an additional apparatus expenditure.